If no Model is specified, an implicit model will be created that implements Ext.data.NodeInterface. The standard Tree fields will also be copied onto the Model for maintaining their state. These fields are listed in the Ext.data.NodeInterface documentation.* According to the Ext.data.NodeInterface documentation:

This class is used as a set of methods that are applied to the prototype of a Model to decorate it with a Node API. This means that models used in conjunction with a tree will have all of the tree related methods available on the model. In general this class will not be used directly by the developer. This class also creates extra fields on the model if they do not exist, to help maintain the tree state and UI. These fields are documented as config options.

I noticed this behaviour only yesterday (NodeInterface gets applied to prototype of my model). My question is how to get my original model fields back? I also use my model in other parts of my app, e.g. in a PropertyGrid which is now populated by unwanted fields!

Thx for your suggestion. I currently just remove all "persitent=false" fields from my object copy that is configured as source in my PropertyGrid. This avoidsappearing the NodeInterface attributes in my grid.